The primary goal of the proposed research is the development of biodegradable polymeric transfection vectors which can be applied to problems associated with human gene therapy. The first half of the proposal details an experimental approach to the synthesis and characterization of new aminc-containing hyperbranched polyesters. These materials have been designed to act as biodegradable analogs of cationic "proton sponge" materials. These "proton sponges," in their current forms, are not biodegradable but demonstrate impressive efficiencies as non-viral gene transfer vectors. The proposed analogs will degrade to non-toxic products under conditions encountered within the cell. The second half of the proposal outlines the specific approaches necessary to determine the biocompatibilities, biodegradabilities, and DNA-complexation profiles of these materials as well as the assays that will be used to determine their efficacies as vectors for the in vitro transfer of plasmid DNA. The proposed materials represent significant advances over existing polymer-based vectors. The biodegradabilities of these new materials may lead to the development of non-toxic highly-efficient polymeric vectors which could eventually be used for the treatment of genetic diseases in vivo.